How to get address to use reflect field?

Question

I got address of a.two.
I want to get same address to use reflect field.

package main

import (
    "fmt"
    "reflect"
)

type A struct {
    one   int
    two   int
    three int
}

func main() {
    a := &A{1, 2, 3}
    fmt.Println(&a.two)

    ap := reflect.ValueOf(a)
    av := ap.Elem()
    twoField := av.Field(1)

    f := twoField.UnsafeAddr()
    fmt.Printf("%v <- want to the same value(address) as the line above.\n", f)
}

I tried to call UnsafeAddr, Addr, ... but, I couldn't get expects value.

score 1 · Accepted Answer · answered Oct 28 '13 at 15:54

You have the right address, it is just not in the right format.

If you convert it to hexadecimal, you get what you want:

package main

import (
    "fmt"
    "reflect"
)

type A struct {
    one   int
    two   int
    three int
}

func main() {
    a := &A{1, 2, 3}
    fmt.Println(&a.two)

    ap := reflect.ValueOf(a)
    av := ap.Elem()
    twoField := av.Field(1)

    f := twoField.UnsafeAddr()
    // %x prints as hexadecimal, prefixing with '0x' to emphasize it
    fmt.Printf("0x%x", f)
}

Feel free to test it.

How to get address to use reflect field?

1 Answers1